Deciding that AI is going nowhere to suddenly deciding that coding agents are how they will work going forward is a radical change. That is what they meant.
Can you explain exactly what you meant by your second paragraph? The ambiguity is why you got that reply.
If your second paragraph makes that reply irrelevant, are you saying the meaning was "Your use of 'radicalized' is technically correct but I still think you shouldn't have used it here"?
https://www.merriam-webster.com/dictionary/paragraph